Oil platforms off the Southern California coast are some of the world's most productive marine fish habitats, a new study has found.
The research could inform decisions to be made about the inevitable decommissioning of the world’s roughly 7,500 oil and gas platforms. Rather than completely removing them, underwater portions could be left intact to provide habitat for increasingly threatened fish populations on natural reefs.
Marine biologists at Occidental College, UC Santa Barbara and the U.S. Bureau of Ocean Energy Management estimated rates of production for the entire community of fish associated with oil platforms, comparing them to previous research that made similar measurements in highly productive estuary, coastal lagoon and coral reef ecosystems.
They found that the platforms tended to produce about 10 times more fish biomass — chiefly various species of rockfish and lingcod — than other more conventional marine habitats studied in the Pacific and North Atlantic oceans, Mediterranean and North seas, the Gulf of Mexico and along the coasts of South Africa and Australia.
When compared to the fish production on natural rocky reefs at similar depths off the Southern California coast, the platforms, on average, produced more than 27 times as much fish, according to the study.
Multiple lines of evidence also suggest that the offshore platforms are not simply drawing fish away from other natural habitats, but producing a net overall increase in the fish population.
"The most exciting thing for me is that this study could provide a basis to start thinking about how to modify new renewable energy-generating structures like wind farms or wave energy devices in ways more beneficial to marine conservation and fisheries," said Jeremy Claisse, adjunct assistant professor of biology at Occidental and study co-author. "From a biological standpoint, the fish don’t know if it’s an oil platform or the bottom of a wind turbine. Complex structures can provide a lot of different kinds of habitat to various species of fish at multiple points in their life cycle."
The researchers next hope to explore how individual platforms contribute to regional fish production in the Southern California Bight, and to better understand what makes one platform more productive than another — insights that could then be used to create fish-friendly designs for other offshore structures.
The new study was published in the Proceedings of the National Academy of Sciences.